Intracellular crystal formation in Bacteroides nodosus

An intracellular crystalline structure was found in at least two strains of Bacteroides nodosus. The inclusion appeared to be associated with good growth of the organism under optimum conditions following selective passage of rough colonies containing highly fimbriate cells. Several morphological forms of the inclusion were noted. Indiscriminate subculture of crystal-forming cultures led to the loss of this particular property indicating a genetically controlled system of either bacterial or bacteriophage origin.